Vm+/Vm- are bipolar power supplies intended to power external multiplexer ICs such as the MAX4051A (maxim-ic.com). The multiplexers can only pass signals within their power supply range, so Vm+/Vm- can be used to pass bipolar signals. Nominal voltage is ±5.8 volts at no load and ±5.6 volts at 1 mA. Both lines have a 100 ohm source impedance, and are designed to provide 1 mA or less. This is the same voltage supply used internally by the UE9 to bias the analog input amplifier and multiplexers. If this supply is loaded more than 1 mA, the voltage can droop to the point that the maximum analog input range is reduced. If this supply is severely overloaded (e.g. short circuited), then damage could eventually occur.

PIN2/PIN20 (TX0/RX0) bring out the UART transmit and receive lines on the UE9, but on other devices they bring out current sources.

In some circumstances it is possible to connect the DB connectors at a severe angle which pushes the internal contacts out of alignment. If you sight down the outside of the female DB connector(s), you should be able to see gold shimmers from within each hole. When the pins get pushed into the connector, or bent, then the gold connector inside won't reflect the light like the other pins do. This visual test is the best way to see if the female connector has a problem.

To re-align the pin, there are 2 options:

1) Open up the LabJack case with a PH1 screwdriver, removing the 6 screws, and look at the DB connector. If the plastic backing seems to be sticking out at all (i.e. the backplate is not flush), then press the plastic backing plate on the DB connector so that it's flush again. This will move any depressed pins back out to the same plane as the rest of the pins.

2) If the pin isn't depressed, but it's instead just bent out of line, use a very small wire or tweezers tip to force the internal pin back into alignment.

The UE9 is not produced in an OEM version, so the DB37 connector would have to be removed post-production. I would not have a recommendation for any higher quality d-sub connectors, as the connectors we use have quality gold-plated contacts and we have not had issues with the contacts. If the pins are in the proper place on the male and female connector (see comment from 13:44 below), we always see good connections.

If the DB37 was removed, you could then install a different DB37, solder wires directly to the PCB, or use the optional holes to install a pin header style connector. See the attachment on the UE9 OEM section. Contact [email protected] if you want a quote for UE9s with connectors removed and/or added.